DE 37 34 462 A1 already describes a planetary gear train of this type having interlocking gearwheels that comprise opposing conically formed teeth, at least one of the two gearwheels being axially moveable relative to the other gearwheel in the direction of the other gearwheel. The planetary gears are mounted on a rotationally fixed shaft that is formed by a pin that is adjustable in the axial direction. The position of the planetary gears cannot be changed during operation, and therefore setting the planetary gears requires the planetary gear train to be disassembled.
DE 94 05 495 U1 discloses, in a gear train, preloading a shaft bearing a conical gearwheel by means of a spring, for example a helical spring, if necessary by the intermediary of a pressure ball, relative to another conical gearwheel.
Tapered, conical gearwheels having a profile offset that is variable over the width are known as gear pairs having parallel axes. Said gearwheels are suitable for setting a backlash-free engagement by means of axial adjustment of one or both gearwheels.
Gearwheel teeth are also used with a high degree of accuracy in planetary gear trains for automatic handling devices (e.g. articulated arm robots, adjustment units, turntables, etc.). Planetary gear trains in these fields are characterized by high transferable torques in compact structural dimensions having very good efficiency levels. Furthermore, these gear trains can later be integrated into machines as a compact unit.
The high power density is achieved by means of a plurality of tooth engagements (sun gear, planetary gears and ring gear). Centre distance variations in the planet carrier as well as manufacturing influences on the teeth (e.g. tolerance fluctuations during production thereof) have a direct influence on the tooth engagements.
With regard to planetary and epicyclic gear trains in particular, which are composed of a plurality of interlocking components and in which the tolerances of the individual components thus have a very significant mutual influence, the manufacturing outlay is comparatively high. The use of tapered or conical gearwheels alone is generally not sufficient either, since the adjustment of one gear pairing can influence the adjustment of another gear pairing (e.g. the adjustment of a plurality of planetary gears acting on one sun or ring gear).
The sun gear and planetary gears must be geometrically arranged inside the ring gear. Since, in practice, there can only be a whole number of gear teeth, the following condition must be met in terms of the number of gear teeth:
                    z        2            +              z        1              q    =      whole    ⁢                  ⁢    number  in which z2=number of gear teeth of the ring gear, z1=number of gear teeth of the sun gear and q=number of planetary gears.